1. Field
The present invention relates to a starter stopper circuit for high-intensity discharge (HID) Lighting sources and ballasts, which includes all pulse start ballasts, such as constant wattage autotransformer (CWA), high reactance auto transformer (HX), and reactor ballasts.
2. Brief Description of the Related Art
High intensity discharge (HID) lighting sources are key light sources for commercial and industrial applications, such as sports stadiums, warehouses, airports, and street lighting. HID lighting sources include mercury vapor, low-pressure sodium, high-pressure sodium, metal halide lamps, and their respective ballasts. HID lamps are widely used because they have a longer life and higher efficiency when compared with fluorescent and incandescent lamps.
Although the operating principle of all HID lamps are similar, the lamp type and wattage vary. Each lamp has a specific lamp current and voltage in a steady state. The ballast of each lamp not only maintains the lamp voltage and current in the steady state, but also produces a sufficient ignition voltage to start the lamp. Generally speaking, a higher wattage lamp requires a higher ignition voltage, thus requiring a larger ballast size. Magnetic HID ballasts represent the majority of HID ballasts.
Recently, electronic HID ballast development has become a trend. Electronic HID ballasts exhibit improved control of the ignition voltage and steady-state lamp power by using integrated circuits. Moreover, electronic HID ballasts can have a universal input voltage while keeping output wattage and light constant.
Commonly used magnetic ballasts include reactor, high reactance autotransformer (HX), and constant wattage autotransformer (CWA) ballasts. A reactor ballast is a single coil ballast. If the input voltage is high enough to start the particular HID lamp and maintain its steady state voltage, the reactor is chosen as a ballast. The advantage of the reactor ballast is that its cost is lower and it is easy to manufacture. An HX ballast is a two-coil ballast, which can step up the input voltage high enough to start an HID lamp. The power factors of both the reactor and HX ballasts can be improved from the normal 50% to a high-power factor 90% by adding a capacitor across the input terminals. Compared with the HX ballast, a CWA ballast has multiple inputs instead of one input and a capacitor in series between a secondary terminal and lamp load. A CWA ballast is the most widely used HID ballast for most applications. A CWA ballast is a high-power factor ballast.
In order to improve lumen efficiency, metal halide lamp structures were developed in the mid 1990s with modified chemistry and fill pressures. This innovation required a higher ignition voltage than the traditional metal halide lamp starting probe and its bimetallic switch could provide. A new device-starter was then developed and used in metal halide lamps. These kinds of lamps are called pulse-start metal halide lamps. The voltage pulse that a starter can generate can be as high as 4000 Vpk.
Since the voltage pulse of a starter is so high, a problem appears in their application. If a lamp comes to the end of its lamp life (cycling, broken, or otherwise no longer functional) and is not replaced in time, both ballast and starter components will bear continuous high voltage pulses until either the ballast, lamp or other fixture component is damaged. Lamp removal, as well as broken, damaged, or bad connections may also result in the same high-voltage stress failure. When the lamp fails and maintenance is not performed, the ballast inevitably fails. Ballast failure is expensive and inconvenient. Thus, one or more solutions to these problems would be advantageous.